Saw chain lubrication means

ABSTRACT

Disclosed herein is a chain saw cutter bar including two side plates having respective inside surfaces defining therebetween a groove adapted for receiving the tangs of a saw chain, together with means in one of the side plates defining a lubrication hole communicating with an oil supply conduit in a supporting chain saw powerhead and including a merging surface which extends in the general direction of intended chain travel and relative to the inside surface of the one side plate at an obtuse angle, whereby to discourage sawdust accumulation in the lubrication hole while affording lubricant flow to the saw chain.

O United States Patent 1191 11 1 3,777,401

Arff et a]. 14 1 Dec. 11, 1973 [54] SAW CHAIN LUBRICATION MEANS2,944,538 7/1960 Conway et al. 83/169 [75] nto we F. r Gordon J. a s,3,279,508 10/1966 Ehlen et al 83/169 222 g: Peterborough Omano PrimaryExaminer-Donald R. Schran a AttorneyRobert E. Clemency et al. [73]Assignee: Outboard Marine Corporation,

Waukegan, Ill. [57] ABSTRACT [22} Filed: Sept. 27, 1971 Disclosed hereinis a chain saw cutter bar including two side plates having respectiveinside surfaces defin- [21] Appl' 183398 ing therebetween a grooveadapted for receiving the tangs of a saw chain, together with means inone of 52 us. c1 30/383, 83/169 the side plates defining av i n holeommuni- 51 Int. (:1 B27b 17/12 eating with an oil pp y conduit in a pp gchain [58] Field of Search 83/169; saw powerhead and including a mergingSurface which 30/331 386 extends in the general direction of intendedchain travel and relative to the inside surface of the one side [56]Reference Cit d plate at an obtuse angle, whereby to discourage saw-UNITED STATES PATENTS dust accumulation in the lubrication hole whileafford- 2,765,823 10/1956 Kneifl 30/386 mg lubncam flow to the Saw cham2,748,810 6/1956 Strunk 30/386 17 Claims, 9 Drawing Figuresv I SAW CHAINLUBRICATION MEANS BACKGROUND OF THE INVENTION Chain saws have beenprovided with arrangements for supplying oil to lubricate the saw chaintraveling in the peripheral groove of a cutter bar. Such arrangementshave commonly included a transverse aperture or oil duct in one of thecutter bar side plates or' rails, which aperture at least partiallycommunicates with the peripheral groove and with an oil'supply conduitprovided in the chain saw powerhead.

The transverse aperture or duct extended generally perpendicularly tothe plane of the cutter bar and provided a surface or shoulder whichalso extended generally perpendicularly of the inside surface of therail in a manner to afford collection and accumulation of wood chips orsawdust in the oil duct. Such accumulation of wood chips and sawdustcould eventually clog the-oil duct and was undesirable.

SUMMARY OF THE INVENTION The invention provides a cutter bar constructedto provide a lubrication hole arranged in a manner so as to avoidsawdust accumulation therein while, at the same time, providing anadequate and reliable arrangement for supplying oil to the peripheralgroove of the cutter bar.

More specifically, the invention provides a cutter bar including alubrication hole having a wall surface which merges with one of thegroove defining surfaces at an angle greater than 90, whereby to avoidformation of a surface which could serve to facilitate sawdustaccumulation.

Still more specifically, in one embodiment of the invention, thelubrication hole is provided by a cylindrical passage which is inclinedtoward the peripheral cutter bar groove in the direction of chain traveland which is additionally inclined outwardly in the direction toward theperiphery of the cutter bar from the outside surface of thebar to anoutlet in the cutter bar groove.

In another embodiment of the invention, there is provided an insertwhich is adapted to be placed in an existing oil duct of a prior artcutter bar and which is formed to provide a lubrication hole with a wallor surface merging with one of the surfaces defining the cutter bargroove so as to avoid accumulation in the lubrication hole of wood chipsor. sawdust, and thereby prevent clogging of the oil passage to thecutter bar groove. One of the principal objects of the invention is theprovision of a cutter bar provided with a non-sawdust cloggingarrangement for supplying oil to the cutter bar groove and ultimately tothe saw chain.

Another of the principal objects of the invention is the provision of achain saw including a system for supplying oil to the saw chain, whichsystem is not subject to clogging by wood chips and sawdust.

Another of the principal objects of the invention is the provision of anarrangement affording ease of modification of existing chain saws andcutter bars to provide a lubrication hole having a surface merging withone of the surfaces defining the cutter bar groove so as to avoid anytendency for sawdust accumulation in the system for supplying oil to thesaw chain.

Still another object of the invention is the provision of a non-cloggingsystem for supplying oil to the periph-' eral groove of a cutter bar,which system can be readily and economically manufactured and which willnot easily clog up with sawdust or wood chips and which will providereliable service overa long and useful life.

Other objects and advantages of the invention will become known byreference to the following description and accompanying drawings.

DRAWINGS FIG. 1 is a fragmentary sectional view of a portion of a chainsaw embodying various of the features of the invention.

FIG. 2 is a fragmentary elevational view, with parts omitted, and withportions broken away, taken from the left of FIG. 1 and illustrating oneembodiment of a cutter bar formed in accordance with the invention.

FIG. 3 is an enlarged fragmentary sectional view of a portion of thechain saw illustrated in FIG. 1.

FIG. 4 is a fragmentary sectional view taken generally along line 4-4 ofFIG. 3.

FIG. 5 is an enlarged fragmentary elevational view of a portion of thecutter bar shown in FIG. 2.

FIG. 6 is a view similar to FIG. 2 illustrating a cutter bar inaccordance with another embodiment of the in vention.

FIG. 7 is an enlarged sectional view taken along line 7-7 of FIG. 6.

FIG. 8 is a fragmentary, enlarged view of aportion of the cutter barshown in FIGS. 6 and 7.

FIG. 9 is an enlarged fragmentary view, partially in section, of anotherconstruction embodying various of the features of the invention.

Before explaining the invention in detail, it is to be understood thatthe invention is not limited in its application to the details ofconstruction and arrangement of parts set forth in the followingdetailed description or illustrated in the accompanying drawings, sincethe invention is capable of other embodiments and of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology or terminology employed herein is for the purpose ofdescription and not of limitation.

DETAILED DESCRIPTION Fragmentarily illustrated in FIG. 1 is a chain saw11 comprising an engine casting or chain saw frame or powerhead 13including a cutter bar mounting surface 17 from which extends a pair ofcutter bar mounting posts 19 (only one of which is shown in FIG. 1). Thechain saw 11 also includes a guide plate 21 which is received on themounting posts 19 and a cutter bar 23 which is located exteriorly of theguide plate 21 with the mounting posts 19 extending in an elongatedmounting slot 27. The cutter bar 23 includes two spaced rails or sideplates 29 which respectively include peripheral surfaces 31 adapted toprovide bearing supchips or sawdust while simultaneously affording areliable supply of oil to the saw chain. The lubricating systemincludes, in the powerhead 13, an oil supply conduit 47 whichcommunicates with a suitable oil pump (not shown) and which terminatesin the cutter bar mounting surface 17, together with means in theadjacent rail or side plate 29 of the cutter bar 23 defining alubrication hole 49 which includes an inlet located in the outsidesurface 37 and communicating with the oil supply conduit 47, whichfurther includes an outlet located in the inside surface 39 andcommunicating with the groove 41, and which still further includes amerging surface 51 which, in the direction of intended chain travel,indicated by the arrow 53 in FIGS. 2 and 4, extends to and in inclinedrelation to the inside rail surface 39, whereby such merging relationavoids sawdust accumulation in the outlet into the groove 41 of thelubrication hole 49.

Various arrangements can be provided to provide such a merging surfaceso as to avoid a surface which is substantially transverse in relationto the direction of travel and located in such position whereby woodchips and sawdust can lodge there-against. In the construction shown inFIGS. 1 through 5, the merging wall surface 51 (See FIG. 4) is providedby formation of the lubrication hole 49 with a drill and at an angle 57which extends, as shown in FIG. 4, at approximately 30 to the directionof intended chain travel as indicated by the arrow 53. As a consequenceof the angular inclination of the lubrication hole just mentioned, themerging surface, seen at 51 in FIG. 4, is provided.

In order to locate the outlet as close to the periphery of the cutterbar 23 as possible, and without adversely affecting the capability forhardening of the peripheral surface 31, the lubrication hole 49 is alsopreferably drilled from the outside surface 37 at an angle of about 30as seen at 59 in FIG. 3. As a result of the inclinations described aboveand shown best in FIGS. 3 and 4, the resulting lubrication hole 49extends obliquely as illustrated in FIGS. 2 and 5 to thereby provide arising oil passage or lubrication hole which extends at an angle 60 ofabout 45 as shown in FIG. 5. Employment of such an inclined lubricationhole serves to locate the inlet at a maximum distance from theperipheral rail surface consistent with locating the outlet as far aspossible from the groove bottom wall 43. Preferably, the outlet iswholly formed in the side rail inside surface 39 and as close aspossible to the peripheral rail surface 31. Such construction affordscomplete wiping of the outlet by the chain tangs to assist in avoidanceof accumulation of sawdust.

Also in accordance with the invention, and in order to insurecommunication with the oil supply conduit- 47, notwithstandingadjustment of the cutter bar 23 in relation to the powerhead 13 toadjust chain tension, the inlet of thelubrication hole 49 is providedwith an enlarged well 61 which extends from the inlet in the outsiderail surface 37 in the general direction counter to the direction ofintended chain travel and inwardly or away from the outer periphery ofthe cutter bar. Such a well can be economically provided in the rail orside plate by a coining operation during the rail blanking operation. Inaddition, the oil supply conduit 47 in the powerhead 13 is preferablyprovided with an enlarged mouth or well 63 which can be elongated in thedirection parallel to the adjustment slot 27 (See FIG. 2), thereby toprovide for continued communication between the lubrication hole 49 andthe oil supply conduit 47, notwithstanding adjustment in the location ofthe cutter bar 23 relative to the powerhead 13. Still further, asuitable bore, opening or slot 67 is provided in the guide plate 21 toafford communication between the well 61 and inlet and the oil supplyconduit 47. This slot 67 can, if desired, be elongated in the directionof cutter bar adjustment to provide for continued communication betweenthe lurication hole inlet and the oil supply conduit 47, notwithstandingthe before mentioned adjustment of the cutter bar 23. With such anelongated slot, the mouth 63 could be formed without material elongationin the direction of cutter bar adjustment. Depending upon the elongationof either the slot 67 or the mouth 63,the location of the lubricationhole can be varied as desired in the direction of cutter bar adjustment.

Preferably, the cutter bar 23 is provided with a duplicate or secondlubrication hole 69 similarly located and constructed in the other railand on the other side of the mounting slot 27.

The invention also extends to arrangements including location of thelubrication hole in the opposite side rail, i.e., in the side railopposite from the powerhead l3, and to provision of a suitablearrangement for supplying oil to the lubrication hole oil inlet in theside plate remote from the powerhead 13.

FIGS. 6, 7, and 8 are illustrative of another arrangement which is inaccordancewith the invention and which includes a cutter bar 77 havingspaced side plates or rails 79 with respective peripheral surfaces 81,outside surfaces 83, and inside surfaces 87 which define therebetween agroove 89 having a bottom wall or surface 91. The cutter bar 77 alsoincludes a mounting slot 93 and pair of spaced apertures 97 which extendtransversely through the rails 79 and, at least in part, communicateswith the groove 89. In the construction specifically disclosed in FIGS.6, 7, and 8, the apertures 97 extend at a right angle to the plane ofthe cutter bar 77 and are elongated along a line extendingperpendicularly to the mounting slot 93 and have semi-circular endportions 99. Approximately the outer half of each aperture 97, i.e., thehalf closest to the peripheral surface 87, opens into the groove 89. Theother or inner half of each aperture 97 is blind. When the cutter bar 77is assembled to a powerhead, one of the apertures 97 is adapted tocommunicate with an oil supply conduit (not shown). As thus fardescribed, the construction of the cutter bar 77 of FIGS. 6, 7, and 8 isconventional.

In accordance with the invention, means are provided for modifyingexisting cutter bars to provide lubrication holes in accordance with theinvention. While various arrangements can be employed in accordance withthe invention, in the construction disclosed in FIGS. 6, 7, and 8, suchmeans includes provision in the aperture 97 communicating with the oilsupply conduit of a lubrication hole 121 which includes a surface 123 inmerging relation with the inside rail surface 87 and which includes anoutlet 127 in co-planar relation to the inside rail surface 87 and aninlet 129 communicating with the aperture 97. Specifically, in theconstruction shown in FIGS. 6, 7, and 8, such means comprises an insert131 received in the bore or aperture 97 and having a flat portion 133defining a planar surface 135 located in co-planar relation to theinside rail surface 87, together with a peripheral flange 139 whichextends the flat portion from the flat portion 135, generally mates withthe wall defining the aperture 97, and has a length approximately equalto the width of the side rail or plate 83.

The insert 131 also includes a merging wall portion 141 which providesthe merging wall surface and which is formed out of the flat portion 133and extends from the flat portion 133. More specifically, themerging'wall portion 141 extends at a relatively small acute angle 143from the flat portion and in a manner such that the distance of themerging wall portion 141 from the plane of the flat portion 133increases in the direction counter to the direction of intended chaintravel indicated by the arrow 147 in FIG. 7. At its outer or free end,the merging wall portion 141 defines, together with the margin of theflat portion 133, the lubrication hole inlet 129 which communicates withthe volume or space at the back side of .the merging wall portion 141and within the confines of the flange portion 133. As already indicated,this space communicates with an oil supplyconduit (not shown) in theengine casting or powerhead, and constitutes an oil reservoir affordingample oil supply to the lubrication hole 121. The area within the marginof the flat portion 133 from which the merging wall portion 141 has beenformed constitutes the lubricating hole outlet 127 to the groove 89.

The insert 13l can be provided with a dimple 149 to indicate the properorientation of the insert 131 in the bore, i.e., location in theaperture 97 such that the merging wall portion 141 inclines toward theflat portion 133 of the insert 131 in the direction 147 of intendedchain travel.

During travel of the chain in the groove of the cutter bar 77 shown inFIGS. 6, 7, and 8, the chain saw tangs successively wipe or'travel pastthe outlet 127 in such manner as to provide a venturi-like effect and todraw oil into the peripheral groove 89 due to such passage. The angularrelationship between the merging wall surface 123 and the flat portion133 which is co-planar to the inside surface 87 of the rail, serves toprevent sawdust accumulation in the lubrication hole 121.

Shown fragmentarily in FIG. 9 is still another construction of alubrication hole 151 provided in a cutter bar 153 in general accordancewith the invention. More specifically, the cutter bar 153 shownfragmentarily in FIG. 9 includes a rail or side plate 157 having anouteror outside surface 159 and an inner or inside surface 161 formingone wall of a groove 163 adapted to receive the tangs of a saw chain(not shown). As in the embodiment shown in FIGS. 6, 7, and 8, the rail157 includes an oil duct or aperture 167. Provided in the oil duct oraperture 167 are a larger insert 169 and a smaller insert 171 which arelocated in facing relation 7 to each other and which define therebetweenthe lubrication hole 151 and additionally provide a merging wall orsurface 173.

More specifically, the larger insert 169 includes a flat portion 175 anda flange portion 179 extending from 175 and having an over-all heightapproximately equal to the width of the rail 157 so that the surface ofthe flat portion 175 is co-planar with the inside rail surface 161.Provided interiorly of the flat portion 175 is a bent portion 181. whichis cut out of the flat portion 175, which extends from the flat portion175 and which provides the merging wall or surface which extends at anangle to, and at an ever increasing distance away from, the insidesurface 161 in the direction counter to the direction of intended chaintravel indicated by the arrow 183.

The smaller insert 171 comprises a similarly shaped disc having acentral portion 187 and a flange portion 5 189 which extends from thecentral portion 187 and is matingly received inside of the flangeportion 179 of the larger insert 169 and which has an over-all heightgenerally equal to the width of the side rail 157 less the thickness ofthe flat portion'175 of the larger insert 169. Provided interiorly ofthe central portion 187 is a bent portion 191 which is cut from andformed out of the central portion 187 and which extends, when thesmaller insert 171 is located in the larger insert 169, in generallyparallel relation to the merging wall surface 173 so as to define,together with the merging wall surface 173, the lubrication hole 151.

If desired, the bent portion 191 of the smaller insert 171 can be formedso as to provide, in conjunction with the larger insert bent portion173, an oil passage or lubrication hole which can either increase ordecrease in size in the direction of chain travel. Of course, the inletend of the lubrication hole 151 communicates with a suitable oil supplyconduit (not shown) in the powerhead and the outlet of the lubricationhole 151 is generally located adjacent to the plane of the inside cutterbar surface 161 with the merging surface or wall 173 forming an angle193 with the inside rail surface 161 of greater than 90 and preferablyas great as about 145.

Various of the features of the invention are set forth in the followingclaims.

1. A chain saw bar for guiding travel of a saw chain, said bar includingtwo side rails having respective outside surfaces and respective insidesurfaces extending in space oppositely facing relation to each other anddefining therebetween a groove which includes a bottom wall and which isadapted for receiving the tangs of the saw chain, and a lubrication holeextending in one of said side rails and including an outlet located insaid inside surface of said one rail above said bottom wall andcommunicating with said groove, said outlet being defined, in part, by amerging surface which, in the general direction of intended travel ofthe saw chain, extends to and in inclined relation to said groove,whereby to discourage sawdust accumulation in said lubrication hole.

2. A chain saw bar in accordance with claim 1 wherein said bar includesan end adapted to be mounted on a chain saw powerhead and wherein saidlubrication hole includes an inlet on said outside surface of said onerail, said lubrication hole extending from said one rail outside surfaceto said one rail inside surface such that said inlet is spaced from theouter periphery of said one rail at a distance greater than the distancefrom the periphery of said one rail to said outlet.

3. A chain saw bar in accordance with claim 1 wherein said bar includesan end adapted to be mounted on a chain saw powerhead and wherein saidlubrication hole includes an inlet on said outside surface of said onerail, said lubrication hole extending from said outside surface to saidinside surface such that said outlet is located in the direction ofintended chain travel ahead of said inlet.

4. A chain saw bar in accordance with claim 1 wherein said lubricationhole includes an inlet with an.

elongated well in the outside surface of said one rail.

5. A chain saw bar in accordance with claim 4 wherein said well iselongated and extends, with respect to the adjacent part of saidlubrication hole, in the direction counter to the direction of intendedchain travel and in thedirection away from the periphery of said cutterbar.

6. A chain saw bar in accordance with claim 1 wherein said lubricationhole outlet is elongated and extends, with respect to the adjacent partof said lubrication hole, in inclined disposition in the direction ofintended chain travel and in the direction toward the periphery of saidcutter bar.

7. A chain saw bar in accordance with claim 1 including two of saidlubrication holes.

8. A chain saw bar in accordance with claim 1 wherein said lubricationhole is elongated in the direction transverse to the direction ofintended chain travel.

9. A chain saw bar in accordance with claim 1 wherein said lubricationhole extends below the bottom of said groove.

10. A chain saw bar for guiding travel of a saw chain, said barincluding two side rails having respective inside surfaces definingtherebetween'a groove which includes a bottom wall and which is adaptedfor receiving the tangs of the saw chain, and means in one of said railsdefining a lubrication hole including an outlet communicating with saidgroove and located solely in said inside surface of said one side railabove said bottom wall and being defined, in part, by a merging surfacewhich extends, in the general direction of intended travel of thesaw'chain and relative to said inside surface of said one rail, at anangle of g reater than 90 whereby to discourage sawdust accumulation insaid outlet.

11. A chain saw comprising a frame including a cutter bar mountingsurface and an oil supply conduit opening into said mounting surface, acutter bar including two side plates having respective inside surfacesdefining therebetween a peripheral groove which includes a bottom walland which is adapted for receiving the tangs of a saw chain, said cutterbar being mounted on said frame with one of said side plates inoverlying relation to said mounting surface, and means in said one sideplate defining a lubrication hole communicating with said oil supplyconduit and including an outlet communicating with said groove andlocated in said inside surface of said one side plate above said bottomwall and being defined, in part, by a merging surface which extends inthe general direction of intended travel of the saw chain and relativeto said inside surface of said one side plate at an angle of greaterthan whereby to discourage sawdust accumulation in said lubricationhole.

12. A chain saw in accordance with claim 11 including a guide platelocated between said cutter bar and said mounting surface and includinga duct communicating between said oil supply conduit and saidlubrication hole.

13. A chain saw in accordance with claim 11 wherein said side plateseach include respective outside surfaces and wherein said lubricationhole includes an inlet on said outside surface of said one side plate,said lubrication hole extending from said outside surface to said insidesurface such that said inlet is spaced from the periphery of said oneside plate at a distance greater than the distance from the periphery ofsaid one side plate to said outlet.

14. A chain saw in accordance with claim 1 1 wherein said side plateseach include respective outside surfaces and wherein said lubricationhole includes an inlet on said outside surface of said one side plate,said lubrication hole extending from said outside surface to said insidesurface such that said outlet is located in the direction of intendedchain travel ahead of said inlet.

15. A chain saw in accordance with claim 11 wherein said side plateseach include respective outside surfaces and said lubrication holeincludes an inlet with an elongated well in said outside surface of saidone side plate.

16. A chain saw in accordance with claim 15 wherein said well iselongated and extends, with respect to the adjacent part of saidlubrication hole, in the direction counter to the direction of intendedchain travel and in the direction inwardly from the periphery of saidcutter bar.

17. A chain saw in accordance with claim 1 1 wherein said lubricationhole outlet is elongated and extends, with respect to the adjacent partof said lubrication hole, in inclined disposition in the direction ofintended chain travel and in the direction toward the outer periphery ofsaid cutter bar.

1. A chain saw bar for guiding travel of a saw chain, said bar includingtwo side rails having respective outside surfaces and respective insidesurfaces extending in space oppositely facing reLation to each other anddefining therebetween a groove which includes a bottom wall and which isadapted for receiving the tangs of the saw chain, and a lubrication holeextending in one of said side rails and including an outlet located insaid inside surface of said one rail above said bottom wall andcommunicating with said groove, said outlet being defined, in part, by amerging surface which, in the general direction of intended travel ofthe saw chain, extends to and in inclined relation to said groove,whereby to discourage sawdust accumulation in said lubrication hole. 2.A chain saw bar in accordance with claim 1 wherein said bar includes anend adapted to be mounted on a chain saw powerhead and wherein saidlubrication hole includes an inlet on said outside surface of said onerail, said lubrication hole extending from said one rail outside surfaceto said one rail inside surface such that said inlet is spaced from theouter periphery of said one rail at a distance greater than the distancefrom the periphery of said one rail to said outlet.
 3. A chain saw barin accordance with claim 1 wherein said bar includes an end adapted tobe mounted on a chain saw powerhead and wherein said lubrication holeincludes an inlet on said outside surface of said one rail, saidlubrication hole extending from said outside surface to said insidesurface such that said outlet is located in the direction of intendedchain travel ahead of said inlet.
 4. A chain saw bar in accordance withclaim 1 wherein said lubrication hole includes an inlet with anelongated well in the outside surface of said one rail.
 5. A chain sawbar in accordance with claim 4 wherein said well is elongated andextends, with respect to the adjacent part of said lubrication hole, inthe direction counter to the direction of intended chain travel and inthe direction away from the periphery of said cutter bar.
 6. A chain sawbar in accordance with claim 1 wherein said lubrication hole outlet iselongated and extends, with respect to the adjacent part of saidlubrication hole, in inclined disposition in the direction of intendedchain travel and in the direction toward the periphery of said cutterbar.
 7. A chain saw bar in accordance with claim 1 including two of saidlubrication holes.
 8. A chain saw bar in accordance with claim 1 whereinsaid lubrication hole is elongated in the direction transverse to thedirection of intended chain travel.
 9. A chain saw bar in accordancewith claim 1 wherein said lubrication hole extends below the bottom ofsaid groove.
 10. A chain saw bar for guiding travel of a saw chain, saidbar including two side rails having respective inside surfaces definingtherebetween a groove which includes a bottom wall and which is adaptedfor receiving the tangs of the saw chain, and means in one of said railsdefining a lubrication hole including an outlet communicating with saidgroove and located solely in said inside surface of said one side railabove said bottom wall and being defined, in part, by a merging surfacewhich extends, in the general direction of intended travel of the sawchain and relative to said inside surface of said one rail, at an angleof greater than 90*, whereby to discourage sawdust accumulation in saidoutlet.
 11. A chain saw comprising a frame including a cutter barmounting surface and an oil supply conduit opening into said mountingsurface, a cutter bar including two side plates having respective insidesurfaces defining therebetween a peripheral groove which includes abottom wall and which is adapted for receiving the tangs of a saw chain,said cutter bar being mounted on said frame with one of said side platesin overlying relation to said mounting surface, and means in said oneside plate defining a lubrication hole communicating with said oilsupply conduit and including an outlet communicating with said grooveand located in said inside surface of said one side plate above saidbottom wall and being defined, in part, by a merginG surface whichextends in the general direction of intended travel of the saw chain andrelative to said inside surface of said one side plate at an angle ofgreater than 90*, whereby to discourage sawdust accumulation in saidlubrication hole.
 12. A chain saw in accordance with claim 11 includinga guide plate located between said cutter bar and said mounting surfaceand including a duct communicating between said oil supply conduit andsaid lubrication hole.
 13. A chain saw in accordance with claim 11wherein said side plates each include respective outside surfaces andwherein said lubrication hole includes an inlet on said outside surfaceof said one side plate, said lubrication hole extending from saidoutside surface to said inside surface such that said inlet is spacedfrom the periphery of said one side plate at a distance greater than thedistance from the periphery of said one side plate to said outlet.
 14. Achain saw in accordance with claim 11 wherein said side plates eachinclude respective outside surfaces and wherein said lubrication holeincludes an inlet on said outside surface of said one side plate, saidlubrication hole extending from said outside surface to said insidesurface such that said outlet is located in the direction of intendedchain travel ahead of said inlet.
 15. A chain saw in accordance withclaim 11 wherein said side plates each include respective outsidesurfaces and said lubrication hole includes an inlet with an elongatedwell in said outside surface of said one side plate.
 16. A chain saw inaccordance with claim 15 wherein said well is elongated and extends,with respect to the adjacent part of said lubrication hole, in thedirection counter to the direction of intended chain travel and in thedirection inwardly from the periphery of said cutter bar.
 17. A chainsaw in accordance with claim 11 wherein said lubrication hole outlet iselongated and extends, with respect to the adjacent part of saidlubrication hole, in inclined disposition in the direction of intendedchain travel and in the direction toward the outer periphery of saidcutter bar.